This is the text of Bertrand Russell's
"Problems of Philosophy".
The notes are by Maarten Maartensz and in another
file, that can be reached when on line by clicking
on the number of the note.

CHAPTER XI

ON INTUITIVE
KNOWLEDGE

THERE is a common
impression that everything that we believe ought
to be capable of proof, or at least of being shown
to be highly probable. It is felt by many that a
belief for which no reason can be given is an
unreasonable belief. In the main, this view is
just. Almost all our common beliefs are either
inferred, or capable of being inferred, from other
beliefs which may be regarded as giving the reason
for them. As a rule, the reason has been
forgotten, or has even never been consciously
present to our minds. Few of us ever ask
ourselves, for example, what reason there is to
suppose the food we are just going to eat will not
turn out to be poison. Yet we feel, when
challenged, that a perfectly good reason could be
found, even if we are not ready with it at the
moment. And in this belief we are usually
justified.

Self-evidence,
however, is not confined to those among general
principles which are incapable of proof. When a
certain number of logical principles have been
admitted, the rest can be deduced from them; but
the propositions deduced are often just as
self-evident (Note 3)
as those that were assumed without proof. All
arithmetic, moreover, can be deduced from the
general principles of logic, (Note 4)
yet the simple propositions of arithmetic, such as
'two and two are four', are just as self-evident
as the principles of logic.

It would seem, also,
though this is more disputable, that there are
some self-evident ethical principles, such as 'we
ought to pursue what is good'. (Note 5)

It should be observed
that, in all cases of general principles,
particular instances, dealing with familiar
things, are more evident than the general
principle. For example, the law of contradiction
states that nothing can both have a certain
property and not have it. This is evident as soon
as it is understood, but it is not so evident as
that a particular rose which we see cannot be both
red and not red. (It is of course possible that
parts of the rose may be red and parts not red, or
that the rose may be of a shade of pink which we
hardly know whether to call red or not; but in the
former case it is plain that the rose as a whole
is not red, while in the latter case the answer is
theoretically definite as soon as we have decided
on a precise definition of 'red'.) It is usually
through particular instances that we come to be
able to see the general principle. Only those who
are practised in dealing with abstractions can
readily grasp a general principle without the help
of instances. (Note 6)

In addition to general
principles, the other kind of self-evident truths
are those immediately derived from sensation. We
will call such truths 'truths of perception', and
the judgements expressing them we will call
'judgements of perception'. (Note 7)
But here a certain amount of care is required in
getting at the precise nature of the truths that
are self-evident. The actual sense-data are
neither true nor false. A particular patch of
colour which I see, for example, simply
exists: it is not the sort of thing that is
true or false. (Note 8)
It is true that there is such a patch, true that
it has a certain shape and degree of brightness,
true that it is surrounded by certain other
colours. But the patch itself, like everything
else in the world of sense, is of a radically
different kind from the things that are true or
false, and therefore cannot properly be said to be
true. Thus whatever self-evident truths
may be obtained from our senses must be different
from the sense-data from which they are obtained.
(Note 9)

It would seem that
there are two kinds of self-evident truths of
perception, though perhaps in the last analysis
the two kinds may coalesce. First, there is the
kind which simply asserts the existence of the
sense-datum, without in any way analysing it. We
see a patch of red, and we judge 'there is
such-and-such a patch of red', or more strictly
'there is that'; this is one kind of intuitive
judgement of perception. The other kind arises
when the object of sense is complex, and we
subject it to some degree of analysis. If, for
instance, we see a round patch of red, we may
judge 'that patch of red is round'. This is again
a judgement of perception, but it differs from our
previous kind. In our present kind we have a
single sense-datum which has both colour and
shape: the colour is red and the shape is round.
Our judgement analyses the datum into colour and
shape, and then recombines them by stating that
the red colour is round in shape. Another example
of this kind of judgement is 'this is to the right
of that', where 'this' and 'that' are seen
simultaneously. In this kind of judgement the
sense-datum contains constituents which have some
relation to each other, and the judgement asserts
that these constituents have this relation.

The case of memory,
however, raises a difficulty, for it is
notoriously fallacious, and thus throws doubt on
the trustworthiness of intuitive judgements in
general. This difficulty is no light one. But let
us first narrow its scope as far as possible.
Broadly speaking, memory is trustworthy in
proportion to the vividness of the experience and
to its nearness in time. If the house next door
was struck by lightning half a minute ago, my
memory of what I saw and heard will be so reliable
that it would be preposterous to doubt whether
there had been a flash at all. And the same
applies to less vivid experiences, so long as they
are recent. I am absolutely certain that half a
minute ago I was sitting in the same chair in
which I am sitting now. Going backward over the
day, I find things of which I am quite certain,
other things of which I am almost certain, other
things of which I can become certain by thought
and by calling up attendant circumstances, and
some things of which I am by no means certain. I
am quite certain that I ate my breakfast this
morning, but if I were as indifferent to my
breakfast as a philosopher should be, I should be
doubtful. As to the conversation at breakfast, I
can recall some of it easily, some with an effort,
some only with a large element of doubt, and some
not at all. Thus there is a continual gradation in
the degree of self-evidence of what I remember,
and a corresponding gradation in the
trustworthiness of my memory. (Note 11)

Thus the first answer to
the difficulty of fallacious memory is to say that
memory has degrees of self-evidence, and that
these correspond to the degrees of its
trustworthiness, reaching a limit of perfect
self-evidence and perfect trustworthiness in our
memory of events which are recent and vivid. (Note 12)

It would seem, however,
that there are cases of very firm belief in a
memory which is wholly false. It is probable that,
in these cases, what is really remembered, in the
sense of being immediately before the mind, is
something other than what is falsely believed in,
though something generally associated with it.
George IV is said to have at last believed that he
was at the battle of Waterloo, because he had so
often said that he was. In this case, what was
immediately remembered was his repeated assertion;
the belief in what he was asserting (if it
existed) would be produced by association with the
remembered assertion, and would therefore not be a
genuine case of memory. It would seem that cases
of fallacious memory can probably all be dealt
with in this way, i.e. they can be shown to be not
cases of memory in the strict sense at all. (Note 13)

One
important point about self-evidence is made clear
by the case of memory, and that is, that
self-evidence has degrees: it is not a quality
which is simply present or absent, but a quality
which may be more or less present, in gradations
ranging from absolute certainty down to an almost
imperceptible faintness. Truths of perception and
some of the principles of logic have the very
highest degree of self-evidence; truths of
immediate memory have an almost equally high
degree. The inductive principle has less
self-evidence than some of the other principles of
logic, such as 'what follows from a true premiss
must be true'. Memories have a diminishing
self-evidence as they become remoter and fainter;
(Note
14) the truths of logic and mathematics have
(broadly speaking) less self-evidence as they
become more complicated. Judgements of intrinsic
ethical or aesthetic value are apt to have some
self-evidence, but not much. (Note 15)

Degrees of
self-evidence are important in the theory of
knowledge, since, if propositions may (as seems
likely) have some degree of self-evidence without
being true, it will not be necessary to abandon
all connexion between self-evidence and truth, but
merely to say that, where there is a conflict, the
more self-evident proposition is to be retained
and the less self-evident rejected.

It seems, however,
highly probable that two different notions are
combined in 'self-evidence' as above explained;
that one of them, which corresponds to the highest
degree of self-evidence, is really an infallible
guarantee of truth, while the other, which
corresponds to all the other degrees, does not
give an infallible guarantee, but only a greater
or less presumption. This, however, is only a
suggestion, which we cannot as yet develop
further. After we have dealt with the nature of
truth, we shall return to the subject of
self-evidence, in connexion with the distinction
between knowledge and error.